Metal-coated iron or steel article.



NIT D STATES PATENT OFFICE.

CLAYTON MARK, JR., AND CLARENCE MARK, F EVANS TON, ILLINOIS, ASSIGNORST0 ANSON MARK AND CLAYTON MARK, COPARTNERS AS THE MARK MANUFACTURINGCOMPANY, OF CHICAGO, ILLINOIS.

METAL-COATED IRON 0R STEEL ARTICLE.

No Drawing.

. To all whom it may concern:

Be it known that we, CLAY'roN MARK, J r., and CLARENCE MARK, citizens ofthe United States, and residents of Evanston, in the county of Cook andState of Illinois, have jointly invented a new and Improved Metal-Coated Iron or Steel Article, of which the following is a specification.

Our invention consists in providing a protective coating for articles ofiron or steel, and is comprised of lead, antimony and zinc in suchproportions that when they are alloyed they are electropositive to iron.

It has been found that where'a coating is applied, such as lead, tin orcopper, which is electronegative to iron, it is almost impossible tosecure a perfect coating; that is, one free from small holes, etc. Insuch a coating, wherever an imperfection occurs, galvanic action is setup between the coating and the exposed iron, so that the iron iscorroded, and after a time the corrosion will eat under the coating andwill cause a separation between the coating and the iron, or else willcompletely destroy the iron. Zinc has been used very largely as aprotective coating, but by reason of the fact that it is veryelectropositive to iron, the zinc coating is destroyed after acomparatively short time by the galvanic action which takes placebetween it and the iron, and it is also readily soluble in acids.

The object of our invention is to provide an alloy of coating of such acharacter that it will not be electronegative to iron, since in such acase a battery action is initiated be- .tween the coating and the iron.at the expense of the iron and which, at the same time, will not betooelectropositive to iron,-

for in such a case the alloy is not durable by reason of the fact that areverse battery action ensues and destroys the coating, and when thecoating has been destroyed the metal itself will become corroded.

We have found it very desirable to use an alloy composed of lead,antimony and zinc, which can be applied to the metal to be pro-Specification of Letters Patent. Patented Jan. 18, 1916. Applicationfiled April 22, 1915. Serial No. 23,105. I

tected at at temperature between 750 and 950 F.

Typical examples of such an alloy are approximately as follows:

Lead Zinc Antimony which we have found to give favorable remac:

temperature is increased, more zinc may beadded, or when the percentageof antimony is increased, the higher is the percentage of zinc which isnecessary to saturate the bath.

An alloy .made in the proportions described maintains a comparativelybright, hard finish, under ordinary conditions of exposure, and is moreresistant to acid attack than the ordinary galvanized coating, orcoatings comprised of lead and zinc. The alloy forms a smooth anduniform coating, which can be readily applied to pipes, sheeting andsimilar articles. We have found this coating to have practically all ofthe advantages of a galvanized or sherardized coating, with the addedadvantage that it is at least twice as durable to weather and acidattack as a galvanized or sherardized coating. It is also much moreadherent than are the usual galvanized coatings, and will not flake orpeel 0E under expansion or contraction of the article, or even if thearticle is bent or hammered. I

The terms and expressions which we have employed are used as terms ofdescription and not of limitation, and we have no intenj antimony andzinc, the antimony beinlg present in percentages below 8 per cent., t ezinc being present in percentages below 6 per cent., and the remamderbeing lead,'the per- 5 centage of antimon being at least as great asthepercentage 0 zinc. a I 7 7 2. An iron or steel article, having a coatingelectropositive to iron, composed "of lead, antimony and zinc, theantimony being p'res- '10 ent between 1 and 8 per cent., the 'zincbeingpresent in percentages between 1 and 6 per 1,1cs ,ees

cent ancl the remainder lead, the percentage of, antimon being at" leastas great as the percentage 0 zinc. I

3. An iron or steel article, having a coat- 15 ing electropositive toiron, containing aproximately the following percentages of cad,antimonyand zinc: ead 92 per cent, antimony 4 .5 per cent. and zinc 3.5per cent.

GLAYTQNMAR JR.

CLARENCE MABK.

